<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        var arr = ['a','b','c','b','vccc' , 'b', 'c', 'b', 'b', 'c', 'b','vvvvv'];

        /*
            通过length属性可以查看当前数组中有多少个值
        */
        // console.log(arr)
        // console.log(arr.length)

        // console.log(arr[0])
        // console.log(arr[1])
        // console.log(arr[2])
        // console.log(arr[3])

        /*
            [] 计算

        */

        console.log(arr[arr.length - 2]);


    </script>
</body>
</html>